INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
ISSN 2277-8616
Design And Construction Of Wireless Charging System Using Inductive Coupling Do Lam Mung, Kyaw Soe Lwin, Hla Myo Tun Abstract: Wireless charging system described by using the method of inductive coupling. In this project, oscillation circuit converts DC energy to AC energy(transmitter coil) to transmit magnetic field by passing frequency and then induce the receiver coil. The properties of Induction coupling are wave(magnetic field-wideband), range(very short~cm), efficiency(hight) and operation frequency(LF-band~several handred kHz).The project shows as a small charging for 5V battery of phone in this method. The system bases on coupling magnetic field, then designed and constructed as two parts. There are transmitter part and receiver part. The transmitter coil (transmitter part) transmits coupling magnetic field to receiver coil (receiver part) by passing frequency at about 1.67MHz. The Ampere’s law, Biot-Savart law and Faraday law are used to calculate the inductive coupling between the transmitter coil and the receiver coil. The calculation of this law shows how many power transfer in receiver part when how many distance between the transmitter coil and the receiver coil. The system is safe for users and neighbouring electronic devices. To get more accurate wireless charging system, it needs to change the design of the following keywords. Keywords: Wireless, power, transfer, inductive ————————————————————
1 INTRODUCTION
2 PROPOSED SYSTEM DESIGNA
WIRELESSpower transfer transfer (WPT) refers to a family of techniques for delivering power without wires or contacts.[1] It was demonstrated firstly by MIT using inductive coupling the summer 2007.[2] In 2008, Intel also achieved wireless power though inductive coupling.[3]Wireless power transfer technology has existed for a long time: however, recent advances have allowed it to become more practical, and recent interest in the consumer market has bought it to the center of attention.[4] This project can be charged several different handheld devices, such as cellular phones and MP3 player (like 5V charging adapter). It can be charged on the surface of the transmitter coil by putting receiving coil at the device. Wireless power transfer means the power supply is not plugged into the device being charged (close proximity or physical contact)[5].
The hardware configuration of wireless power transfer system is basically on inductive coupling method. The complete circuit diagram of project can be divided in two different sections: • Transmission section and • Receiving section In transmission section, oscillation circuit operates as pushpull devices to transmit magnetic field to the receiving coil. The system uses coupled magnetic fields as a frequency to transfer electromagnetic energy from the transmitter to receiver.[6] Fig2 show the circuit diagram of transmission section. 12V D3
C17
12V Battery
Oscillator Circuit (1.67MHz)
R1
L1
D2
C9
C2
C10
C3
C11
C4
C12
T1
Transmitter Coil Relay
C1
R3
L3
C18
Charging Battery
DC Level Stabilizer
Receiver Coil D4
R2
Fig. 1.Block diagram of wireless power transfer system
T2
L2 D1
C5
C13
C6
C14
C7
C15
C8
C16
R4
In this project, supply voltage 12 DC drives oscillator circuit as push-pull driver to operate transmitter coil. Then, the transmitter coil transmits coupling magnetic field by passing frequency at about 1.67MHz. In this state, there are AC voltage and the receiver coil receiver coupling magnetic field as ACvoltage. DC level stabilizer converts AC to DC voltage again to charge the battery of device.
C17=220nF, C18=0.22uF, C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11=C12=C13=C14=C15= C16=0.1uF, Relay=12V R1=R2=100Ω(2W), R3=R4=5.6kΩ, D1=D2=D3=D4=6A10MICdiode L1=L2=28.18uH(8-turns, FT50-43,ferrite core) L3=1 turn(220mm diameter,13mm copper tube) T1=T2=IRF 2807 (n-channel) Fig. 2. Circuit diagram of Transmission section
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Do Lam Mung is currently pursuing masters degree pro-gram in electronic engineering in Mandalay Technological University, Mandalay, Myanmar, PH+959402638908. E-mail:
[email protected] 282 IJSTR©2015 www.ijstr.org
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
DC level stabilizer
Receiving coil
Diode LM317T
IN
OUT ADJ
12V,5W Lamp
Diode
C2 Diode
+ Diode
Diode
C1
C3
Diode
R1
R2 C5
USB wire to phone
-
L4=1turn (220mm diameter, 13mm copper tube), C1=0.02uF, Diode=1N4007, C2=470uF, C3=1uF, R1=47Ω, C4=10uF, VR=5kΩ, C5=1uF, R3=100kΩ, R4=11.11kΩ Fig. 3. Circuit diagram of Receiving section
C9
C2
C10
C3
C11
C4
C12
L3
C5
C13
C6
C14
C7
C15
C8
C16
Fig. 5. Frequency oscillation by Inductor coil and Capacitors
2.1 OPETATION OF POWER MOSFETT1 AND T2 When T1 is LOW (off) and the pass transistor gate is pulled up to T2 to keep it turned on. When T1 is HIGH(on), the pass transistor gate is pulled to ground, and the transistor T2 turns off.
f=1/2 π √LC=1.57MHz
+12V
+12V
L1
L1 D3
R1
C1
C18
C4
L4
ISSN 2277-8616
Vout
Vout D2
T1
Rds(ON) Switch”closed”
+12V R3
R2
+12V
+12V
L2
L2 Vout
R2
D2 T2
Vout
Switch”open”
+12V R4
Fig. 4. Power mosfet T1 HIGH(on) and T2 LOW(off)
2.2 CALCULATION OF FREQUENCY(C AND L) AND COIL DESIGN The frequency oscillation is calculated as the following: 1/Ca=1/C1+1/C2+1/C3+1/C4, Ca=25nF 1/Cb=1/C5+1/C6+1/C7+1/C8, Cb=25nF 1/Cc=1/C9+1/C10+1/C11+1/C12, Cc=25nF 1/Cd=1/C13+1/C14+1/C15+1/C16, Cd=25nF Ca,C18 and Cb are series, Cx=11.83nF Cc and Cd are series, Cy=12.5nF Cx and Cy are parallel, C=24.5nF
Fig. 6.Copper tube(13mm diameter) and Diameter of coil
3 HARDWARE IMPLEMENTATION The hardware design of wireless charging system describes as two sections. (1). Transmitter section and (2). Receiver section Transmitter section consists of electronic parts shown as the circuit diagram fig 2. It drives as push-pull deriver (alternate power mosfet transistors T1 and T2) to transfer magnetic field (inductive coupling) by passing the frequency oscillation about 1.67MHz.
283 IJSTR©2015 www.ijstr.org
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
ISSN 2277-8616
3.1 CALCULATION OF M AGNETIC FIELD(B) AND DISTANCE(X) (A) PRIMARY COIL Biot-Savart law gives out the magnetic flux density generated by the flow of charges:
Where; r=the full displacement vector from wire element to the point er=the unit vector of r Idl=linear-current-element in the wire µ0=the magnetic constant Fig. 7.The project of transmitter section Receiver section is used for to receive power by magnetic field and passing the frequency oscillation. In this state is AC voltage and then it needs to convert DC voltage for charging the battery of phone.
For the circular coil, the generated magnetic flux density B the point x;
at
a=110mm=11*10-2m, let x=5cm=5*10-2m, Ip=I=11.6A Bx=5*10-5exT V0(t)=2Vmsinθ (Vm=12V,Vp=2Vm) θ=0, 90, 180, 270, 360,… Vp=V0=0V, 24V, 0V, -24V, 0V, … Fig. 8.The project of receiver section +Vp 0 90
180 270 360 ...
-Vp
Fig.10. Calculation by Power Mosfet T1 and T2 passing L and C (B) SECONDARY COIL
Fig. 9.The wireless charging system of mobile phone
The total time-varying magnetic flux φm crossing the secondary coil can be expressed by: 284 IJSTR©2015 www.ijstr.org
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
ISSN 2277-8616
3.2 CALCULATION OF TRANSMITTER AND RECIVER COILS (L3=L4=1TURN=420NH) According to the Faraday’s law of induction, the induced voltage in the secondary coil is:
y
x
a
.
B x
Fig. 11. Angle between the magnetic field and receiving coil φm(t)=∫sB.dS=NBA cosa coswt=NBAcoswt (a=0) V(t)=-d φm(t)/dt=-NBA d/dt coswt=NBAwsinwt=NBAwsinθ θ=0, 90, 180, 270, 360 N=1, Bx=0.5µexT, A=πr2 (r=11*10-2m), w=2πf (f=1.25MHz) Vp=0V, 15V, 0V, -15V, 0V (distance between 5cm transmitter and receiver)
Fig. 14. Transmitter coil and receiver coil (13mm copper tube and 22omm diameter) The number of turn to get L3=L4=1turn=420nH calculates as the following: L= µ0N2A/ℓ From
3.1 CALCULATION BY DIGITAL OSCILLOSCOPE
emf=∫CEdℓ=-d/dt∫ABdA
[the induction theorem (in general form)] and e.m.f=d/dtφ(Faraday’s law) Air core coil (L3=L4=420nH transmitting and receiving coils) ℓ=the length of the gap=diameter of the coil ℓ =220mm=22cm=22*10-2m r=11cm=11*10-2m, L=420nH, A= π r2,µ0=4π *10-7H/m Get :N=1.3≈1 turn
3.3 CALCULATION THE NUMBER OF TURNS IN CHOKE The inductance of inductor with toroidal core calculates in the following:
Fig. 12. Waveform of Vp(Primary coil) In the transmitter coil; Vp=24V, f=1/T=1/800ns=1.25 MHz (T=800ns)
Fig. 15.The inductance of inductor with toroidal core L=λ/I =µrcµ0hN2/2π Ln(b/a) From ∫cH.dl= NI (dl=rdφ) ( Applying Ampere’s law) L=28.18uH,µrc=800,µ0=4π*10-7H/m, h=0.47752*10-2m, a=0.35687*10-2m,b=0.635*10-2m, Get: N=8 turns
Fig. 13. Waveform of Vp(Secondary coil) In the receiver coil; Vp=15V, f=1/T=1/800ns=1.25 MHz (T=800ns) 285 IJSTR©2015 www.ijstr.org
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
3.4 CALCULATION BY DIGITAL VOLTMETER (DC VOLTAGE)
ISSN 2277-8616
by both power mosfet transistors.
Fig. 16. DC Voltage and Ampere(between transmitter and receiver=1.3inches) P=VI=1.005*7.63=7.4W (Loading 10Ω,5W)
Fig. 18. Multisim Test for Wireless Power Transfer Circuit
Fig. 19. Frequency oscillation by simulation, XSC1 (both of power mosfet transistor T1 and T2) Fig. 17. DC Voltage and Ampere (between transmitter and receiver=4inches) P=VI=145.1m*1.22=0.18W (Loading 10Ω,5W)
3.5EFFICIENCY, Ƞ EFFICIENCY,Ƞ={P(RECEIVING COIL) / P (TRANSMITTING COIL)}
Fig. 20. Frequency oscillation XSC2 by power mosfer transistor T1
Calculation of 1.3inches=transmitting coil and receiving coil; P(receiving coil)=7.4W P(transmitting coil)=12*1.3=15.6W Get; Efficiency,Ƞ=0.47=47%
4 SIMULATION RESULT In simulation, it shows the calculation of the waveform, DC voltage waveform by each power mosfet transistor, AC voltage 286 IJSTR©2015 www.ijstr.org
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 06, JUNE 2015
ISSN 2277-8616
[4] A.Kurs, A.Karalis, R.Moffatt, J.D.Jounnopoules, P. Fisher and M. Soljacic, “Wireless power transfer via strongly coupling magnetic resonances”,( Science, vol.317, pp.83-86, 6 June 2007). [5] Allen T.Waters for the degree of Honors Baccalaureate of Science in Electrical and Computer Engineering presented on May 28,2010. [6] @watch?v=hZ8Z07fOOqwhttps: //www.youtube.com/watch?v=2Av_sbU9lAI
Fig. 21.Frequency oscillation XSC3 by power mosfer transistor T2
f = 1/T = 1/617.424n = 1.65MHz Fig. 22. Calculation of frequency oscillation by simulation
5 CONCLUSION Wireless power transfer by inductive coupling is described in this paper. In this circuit project, power transfer about 7.4watt when the transmitter and receiver are between 1.3inches. It needs to redesign and reconstruct by changing power mosfet transistor. In the paper, the design is not perfect and redesign in this jounal. The components need to change. Wireless power transfer system can be realized to perform to high standards followed more distance between transmitter and receiver by changing the size of copper wire guage or copper tube and design of inductance in toroidal core.
ACKNOWLEDGMENT The author would like to thank to Dr. Hla Myo Tun, Associate Professor and Head of the Department of Electronic Engineering, Mandalay Technological University for his help. And thanks to the supervisor, Dr. Kyaw Soe Lwin, Lecturers, Department of Electronic Engineering, Mandalay Technological University for his guidance, support and encouragement.
REFERENCES [1] Program on Technology Innovation: Impact of Wireless Power Transfer Technology (Initial Market Assessment of Evolving Technologies-Final Report, December 2009). [2] Final Paper Wireless power transfer “Daniel Deller, Skip Dew, Justin Freeman, Custis Jordan, Ray Lecture, Malik Little”, Thusday, December 11, 2008. [3] M.Longer, “Wireless power & “Sensitive” Robots”,[Organization website], [Cited 1 September 2008], Available HTTP: 287 IJSTR©2015 www.ijstr.org